<HTML>
<HEAD>
<META content="text/html; charset=iso-8859-1" http-equiv=Content-Type>
<META content="OPENWEBMAIL" name=GENERATOR>
</HEAD>
<BODY bgColor=#ffffff>
Hi Alireza,
<br />
<br />next to surface, where the air density (rho) is about 1.2 kg/m^3, a w=1 m/s gives omg=11.8 Pa/s.
<br />In your example, your omg~0.1 Pa/s, so it is a low value. In large-scale, the vertical motion is actually low.
<br />
<br />In thunderstorms (and clusters of thunderstorms as well, which are mesoscale in temporal and spatial range), however, w can frequently be > 20 m/s. If you are dealing with large-scale (synoptic scale) data, your data will not be able to "see" thunderstorms.
<br />
<br />What are the dx and dy intervals of your data? Probably your data can not explicitly resolve big vertical motions. Try to compute w in a region where there is a cold front in activity at, for example, 700 mb level.
<br />
<br />Hope this helps,
<br />Ricardo
<br />
<br /><font size="2"><b>On Wed, 16 Nov 2011 04:32:43 +0330, Alireza Azargoun wrote</b>
<br />> thnx
Tereza
<br />>
<br />> but I don't understand it. did you mean that my
answer [W=0.00912 (m/s)] is not (m/s) and it's in (cm/sec)!? supposing that
isn't a 0.912 cm/sec a low speed vertical velocity airflow!? if there's
any reference on this subject I'll be glad if you anyone notify me about it.
<br />>
<br />> On Wed, Nov 16, 2011 at 4:18 AM, <span dir="ltr"><<a href="mailto:tcavazos@cicese.mx">tcavazos@cicese.mx</a>></span>
wrote:
<br />> <blockquote style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;" class="gmail_quote">
Hi
<br />>
<br />>
The usual unit (magnitude) of vertical velocity is in cm/seg.
<br />>
So, it is fine.
<br />>
<br />>
Cheers,
<br />>
Tereza
<br />>
<br />>
> Dear GrADS users
<br />>
> Hi
<br />>
>
<br />>
> I'm recently working on a project about the vertical speed of air
in
<br />>
> different elevations. I'm using CFSR data in grb2 format. these data
sets
<br />>
> have omega (Pa/s) instead . I tried to convert them to vertical
velocity
<br />>
> (m/s) using this equation:
<br />>
> omega= - rho * g * w ( or omega=- (P/RT) *g * w )
<br />>
> but the results in (m/s ) are in the order of 10^-3. I know it's not
a
<br />>
> Grads problem. but I'm an aerospace student and I need to find out
if
<br />>
> anything is wrong with this equation or the results or not. ( I'm
not
<br />>
> really familiar with meteorology!)
<br />>
>
<br />>
> for example:
<br />>
> if omega= 0.10595
<br />>
> & g=9.807
<br />>
> & R=287
<br />>
> & P= 100000 Pa
<br />>
> & T=294.27
<br />>
> resulted value is W=0.00912 (m/s)
<br />>
>
<br />>
>
<br />>
> Thanks in advance,
<br />>
> Alireza
<br />>
> _______________________________________________
<br />>
> gradsusr mailing list
<br />>
> <a href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a>
<br />>
> <a target="_blank" href="http://gradsusr.org/mailman/listinfo/gradsusr">http://gradsusr.org/mailman/listinfo/gradsusr</a>
<br />>
>
<br />>
<span class="HOEnZb"><font color="#888888">
<br />>
<br />>
--
<br />>
Tereza Cavazos
<br />>
Departamento de Oceanografia Fisica
<br />>
CICESE
<br />>
Ensenada, Baja California, MEXICO
<br />>
<a target="_blank" href="http://usuario.cicese.mx/%7Etcavazos/">http://usuario.cicese.mx/~tcavazos/</a>
<br />>
<br />>
_______________________________________________
<br />>
gradsusr mailing list
<br />>
<a href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a>
<br />>
<a target="_blank" href="http://gradsusr.org/mailman/listinfo/gradsusr">http://gradsusr.org/mailman/listinfo/gradsusr</a>
<br />>
</font></span></blockquote>
<br />>
<br clear="all" />
<br />> --
<br />> Alireza
Azargoun
<br />
</font>
</BODY>
</HTML>